Wednesday, December 15, 2010

Starting a Yeast Culture

This morning I woke up and decided it is time to grow my own yeast. Why? Because I can. So I searched my two favorite sources: teachers websites and public databases of scientific articles.

From ACS Publications (which I've actually never used)

Aeration Studies on Propagation of Baker's Yeast

William D. Maxon, Marvin J. Johnson
Ind. Eng. Chem., 1953, 45 (11), pp 2554–2560

"1. The organism grows well on a completely synthetic medium with glucose as the sole source of carbon.
2. The over-all metabolism of the organism is simple.  The only major products are yeast cells, ethanol, and carbon dioxide.
3. The process requires air. The absence of air causes an easily measured change in metabolism, the increased rate of formation of ethanol.
4. The organism is enzymatically stable and is relatively easy to keep free of contaminating microorganisms."

Your First Microbiology Experiment Revision #3

Harold Eddleman, 1998, Indiana Biolab, Palmyra IN

This gave me information on medium, feed, sterilization and more. This Doctor and President of this particular biology lab also seems to have many linking sites for biology classes/studies.

No need to sterilize because the yeast kills other bacteria or interferes with other organism growth.

Temperatures should be relatively high which anyone who has watched bread rise knows.  My house is not usually warm because I mainly heat with wood and let it dwindle at night. But I'll give it a try anyway by placing it in the highest corner cabinet of my kitchen where the temp currently read 69F.

Yeast  Culture    Fleishmann's Active Dry Yeast Ingredients: yeast, sorbitan monostearate. (I'll find out what that is later)
Medium             Well water
Food                   Great Value Light Corn Syrup Ingredients: light corn syrup, water, high fructose corn syrup (that is really what I want), salt, vanilla
Container          Glass peanut butter jar with lid ajar for aerobic needs
Temperature     a range of 50F-80F

I wander whether the extra ingredients in the corn syrup; vanilla especially, will change the flavor of the yeast.  If the yeast does not grow I may have to find a medium that contains extra elements it may need, such as nitrogen. Or find a warmer spot.

Will this be a liquid yeast? How do I make dry yeast?

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